> I'm quite sure Boeing knows the answer to these questions. I suspect the FAA knows the answer to these questions. And when you say "we don't know" I think you

> I'm quite sure Boeing knows the answer to these questions. I suspect the FAA knows the answer to these questions. And when you say "we don't know" I think you mean HNer's engaged in discussion, who maybe aren't even aware that quite a lot of things are mandatory for obtaining transport category aircraft airworthiness certification. I mean that the general public doesn't know that indeed. And thanks for the references, I'll look them up. The original post I replied to was specifically saying that what you are now describing is not allowed (these types of planes being unstable) should be acceptable.